[Modification of the method of preparation of paraffin blocks]

The quality of paraffin sections is determined to a considerable degree by the properties of paraffin block such as crystal size and spatial homogeneity. A new temperature regimen of treatment in preparation of paraffin blocks has been developed. After impregnation, pieces of tissue are overlayed with paraffin at a temperature of 56-60 degrees C in paper-tin foil dishes and then immediately placed in an antifreeze at 0 degree to -5 degrees C. The internal stresses, deformations, and microcracks occurring in this procedure are eliminated by incubation of the resulting block in a thermostat at 45 degrees C in vapours of low-melting fraction of paraffin (2-24 hours) followed by rapid cooling with cold air (from -5 degrees to -10 degrees C). The second step of the treatment may also be used for improvement of the quality of paraffin blocks after long-term storage.